The invention relates to a knotcatcher for and a yarn delivery device for textile machines in general, and particularly to an air jet loom utilizing such yarn delivery device. In textile machinery there often is provided a device for measuring a predetermined length of yarn, thread, or the like that is to be fed to other portions of the machine. For instance, air jet looms require a measuring device for measuring the length of yarn necessary for each weft insertion. In such machines, and particularly air jet looms, it is desirable to provide such measuring devices that have no substantial adverse impact on the yarn being measured and delivered thereby, which are easy to construct and repair, and which have long life and use.
Conventional yarn length measurement and delivery devices, particularly for air jet looms, do not always have the desired qualities set forth above. For instance conventional yarn measurement and delivery devices associated with the ELITEX air jet loom manufactured by Investa of Prague, Czechoslovakia have a knotcatcher (also known as a filling snubber wheel) made of an aluminum composition having a plurality of sawtooth teeth extending axially from a circular plate and adapted to move into the yarn path to catch the yarn and cause it to be taken up upon a rotary measuring drum. The sawtooth teeth provide significant resistance to yarn release, requiring a relatively large amount of air pressure to pull the yarn from the measuring drum for a weft insertion. Since the efficiency of the loom, the cost of operating the loom, and the quality of the fabric produced are all greatly affected by the ease in which the yarn is pulled from the filling feeder into the jet, this is undesirable. Additionally, the teeth wear the yarn contact points. Further, replacement of the knotcatchers due to wear is more frequent than desirable, and when a tooth is damaged the knotcatcher must be discarded since there is no adequate mechanism for reattaching the tooth or substituting a new tooth in its place.
According to the present invention, a knotcatcher for and a yarn measurement and delivery device for textile machines, and particularly for use in an air jet loom, is provided that overcomes the problems inherent in prior art devices such as discussed above. In particular, according to the present invention a knotcatcher associated with the yarn delivery device is provided that has minimal resistance to the yarn requiring a minimum amount of air pressure to release the yarn from the knotcatcher and measuring drums. Additionally, the yarn arresting projections formed on the knotcatcher according to the present invention have smooth, curved surfaces so that wear on the yarn at the contact points is reduced. The knotcatcher arresting projections further are constructed so that they may be readily replaced if worn or damaged, and are of hardened steel so that they have a long loom life.
In particular, an exemplary yarn delivery device, for textile machines, according to the present invention includes a stationary housing with a yarn inlet and outlet defining a yarn path, a lipped measuring drum mounted for continuous rotation within the housing, and a knotcatcher mounted for rotation with the measuring drum and for axial movement with respect to the measuring drum from a position within the volume defined by the measuring drum lip to a position axially outwardly past the measuring drum lip into the yarn path, as is conventional. The knotcatcher in accordance with the invention has as its axially extending projections a plurality of smooth-surfaced cylindrical pins. The pins preferably are hardened steel, preferably having a circular cross-section with a diameter of about 1/16 inch and a length of about 0.4 inches. The pins are replaceably mounted in the knotcatcher circular plate. This is preferably accomplished by forming a peripheral circular rim upstanding from one surface of the knotcatcher plate and providing a plurality of through-extending holes in the rim, dimensioned and shaped to receive an end of a pin with a press fit. Preferably 72 pins are disposed around the rim. In order to provide proper balance and weight of the knotcatcher plate (which may be made from an aluminum alloy such as aluminum 6061T6), a plurality of symmetrically shaped, sized, and spaced holes may be formed in the plate within the area defined by the rim.
The yarn delivery device according to the present invention is particularly adapted for use with an air jet loom including an air jet for weft insertion, a confuser channel operatively associated with the air jet, and yarn severing means associated with the confuser channel for cutting off yarn after a weft insertion. Yarn from a supply bobbin supported by appropriate means associated with the loom is fed to the yarn measuring and delivery device according to the invention, the appropriate length is measured thereby, and upon actuation of the air jet the necessary yarn length is inserted into the confuser channel from the delivery device.
It is the primary object of the present invention to provide a yarn delivery device for textile machines having a knotcatcher effecting minimum wear of the yarn, having minimal resistance to yarn removal, and having long loom life. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.